1. Field of the Invention
The invention relates to excimer laser eye surgery systems, and more specifically to distributed topography, treatment creation, and excimer laser system.
2. Description of the Related Art
Excimer laser eye surgery systems are becoming a more often used system for correcting vision. From eye glasses to radial keratotomy, ophthalmic surgery has now progressed to a point where the surface of the eye is actually reshaped using cold light laser ablation provided by excimer lasers, typically argon fluoride lasers operating at around 193 nanometers. These lasers are even used to reshape the stromal tissue underneath the surface of the eye in a laser in situ keratomileusis technique patented by Gholam Peyman in U.S. Pat. No. 4,840,175, which is hereby incorporated by reference.
These techniques start with the uncorrected profile of the eye, and then ablate the eye using various small or large beam techniques, or aperture techniques, to reprofile the surface into a desired, corrected profile. The amount of correction is determined by a variety of methods, but for myopia, for example, given the starting curvature of the eye and the amount of dioptric correction needed, equations are well known which specify the amount of tissue that must be removed from each point on the surface of the eye. These equations are found, for example, in assignee's PCT patent application serial no. PCT/EP93/02667, as well as the U.S. counterpart to that application, Ser. No. 08/338,495, filed Nov. 16, 1994, which is hereby incorporated by reference. Similar equations are known for the amount of tissue necessary for removal to correct for hyperopia and astigmatism.
Before relying on these equations, however, the actual curvature of the eye must be determined. This is done using a number of techniques. The patient's visual acuity can be determined through eye exams. The actual shape of the surface of the eye can be determined, for example, using a topography system. These topography systems can be either manual or computerized, and the latter can provide a point-by-point representation of the curvature of the eye, for example, in the form of an axial curvature, the instantaneous or true local curvature, or the absolute height.
Typically, based on these curvatures and the patient's visual acuity, the doctor programs into an excimer laser surgery system an amount of positive or negative dioptric correction (depending on whether the correction is for hyperopia or myopia) and an angle of the cylinder of astigmatism, if any, along with the amount of dioptric correction necessary for the astigmatism. Software within the excimer system itself then calculates the necessary shot pattern and that pattern is executed on the surface of the patient's eye.
Such a system, however, places limits on the different types of vision defects that can be corrected. Further, it would be desirable to more efficiently use expensive resources in such systems.